Deep-drawn marine hull having a sandwich structure and watercraft utilizing same

ABSTRACT

A deep-drawn, marine hull having a sandwich structure and watercraft utilizing same are provided. The hull includes an outer skin having a waterproof outer surface, an inner skin having a compartment-defining outer surface and a shock absorbing, cellular core positioned between the skins. The skins are bonded to the core by press molding. The cellular core has a 2-D array of cells, each of the cells having an axis substantially perpendicular to the outer surfaces. Thickness of side walls of the hull is substantially uniform to maximize stiffness of the hull. The cells absorb energy of an impact at the outer surface of the outer skin by deformably crushing. Air trapped within cells which are not completely crushed or punctured by the impact provide the hull with buoyancy to allow the hull to float at the surface of a body of water.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part application of U.S. patentapplication entitled “Assembly Including a Compression-Molded CompositeComponent Having a Sandwich Structure and at Least One FastenerComponent” filed May 24, 2012 and having U.S. Ser. No. 13/479,974.

TECHNICAL FIELD

This invention generally relates to stiff or hard marine hulls and, inparticular, to watercraft such as kayaks which utilize such hulls andwhich have a sandwich structure.

OVERVIEW

Small, portable boats or watercraft come in a wide variety of models,sizes, colors and design configurations. Hulls must typically belightweight, durable, strong and stiff. Such boats are oftentimes usedfor hunting, fishing and, consequently, require a large amount ofstorage space. Kayaks, canoes and row boats are examples and typicallyrequire room for seats.

One type of such watercraft is skin-on-frame or skin boats. These arethe most commonly available portables and are made by stretching a“skin” or cover of waterproof material over a framework or skeleton. Oneproblem with such boats is the puncture problem. A sharp rock or apointed piece of submerged metal can create a hole or opening in theboat hull to cause the boat to sink as shown in FIGS. 1 and 2. Water 30flows in the direction of arrows, F, through an opening 34 in a single,metal wall 12 as shown in FIG. 6. This problem can result even if thehull is double-walled 12 as shown in FIG. 7.

Another type of such watercraft have foldable hulls. U.S. Pat. No.6,615,762 discloses a boat made of extruded corrugated plastic which istypically lightweight. The boat hull includes flat blank hull sectionswith fastener holes and hinge score lines. The hull sections are foldedinto the desired shape at the score lines which form living hinges.

One problem associated with such hulls is the large number of partsrequired to assemble the boat. Another problem is the faceted outline ofthe boat diminishes the speed and maneuverability of the boat. Also,interior flanges or ribs reduce the amount of space for one or morepassengers and gear.

Another type of such watercraft are rigid or “hard shell” canoes orkayaks. They are typically made of rotomolded or thermoformed plastics,fiberglass or plywood. However, their weight makes them difficult totransport.

The following U.S. Patents are also related to the present invention:U.S. Pat. Nos. 8,316,788; 8,069,809; 7,963,243; 7,854,211, and7,530,322.

It is highly desirable to secure hardware and other components to marinehulls and watercraft which utilize marine hulls. It is desirable toprovide attachment mechanisms at various locations to secure cargo suchas gear to protect the cargo from sliding, rolling, etc. which tends todamage the cargo as well as other items or structures in the cargo area.

Because of the large forces that cargo as well as individuals can exerton marine hulls, any attachment or fastening mechanism must be able towithstand not only large pull-out forces but also large push-in forces.Also, such attachment or fastening mechanisms must be able to withstandlarge torque forces to prevent the mechanisms from being “torqued out”of or “torqued into” the hull.

Compression molding has long been used to manufacture plastic parts orcomponents. While widely used to manufacture thermoset plastic parts,compression molding is also used to manufacture thermoplastic parts. Theraw materials for compression molding are typically placed in an open,heated mold cavity. The mold is then closed and pressure is applied toforce the materials to fill up the entire cavity. A hydraulic ram orpunch is often utilized to produce sufficient force during the moldingprocess. The heat and pressure are maintained until the plasticmaterials are cured.

Two types of plastic compounds frequently used in compression moldingare Bulk Molding Compound (BMC) and Sheet Molding Compound (SMC).

In general, compression molding provides good surface finish and can beapplied to composite thermoplastics with woven fabrics, randomlyoriented fiber mat or chopped strand. One of the problems associatedwith compression molding is that compression molding is thought to belargely limited to flat or moderately curved parts with no undercuts.

Some compression-molded composites combine a light-weight, low-densitycore with fiber-reinforced thermoplastic skins or outer layers therebyresulting in a sandwich structure. The resulting composite component hasa high stiffness-to-weight ratio thereby making it desirable for use ina wide variety of applications including load-bearing applications. Ingeneral, the thicker the core, the higher the load-bearing capacity ofthe composite component.

As a result of their high stiffness-to-weight ratio and load-bearingcapacity, such compression-molded composites have been used as loadfloors (U.S. Pat. No. 6,843,525) in automotive applications and as skisor snowboards (i.e., sliding boards) in recreational applications.

The prior art discloses a method of making a panel of sandwich-typecomposite structure having a cellular core in a single processing step.In that method, the panel as shown in FIG. 4 is made by subjecting astack or blank of layers of material to cold-pressing in a compressionmold. As shown in FIG. 3, the stack is made up of: at least a first skinmade of a stampable reinforced thermoplastics material, a cellular coremade of a thermoplastics material, and a second skin also made of astampable reinforced thermoplastic material. The skins are typicallypre-heated outside the mold to a softening temperature.

Such a method is particularly advantageous because of the fact that itmakes it possible, in a single operation, to generate cohesion andbonding between the various layers of the composite component shown inFIG. 4, and to shape the resulting component while preserving all of themechanical properties imparted by the cellular-core sandwich structure.

Panels of sandwich-type composite structure having a cellular core haverigidity characteristics sufficient to enable mechanical structuressubjected to large stresses to be reinforced structurally without makingthem too heavy. Such panels are in common use in shipbuilding, aircraftconstruction, and rail vehicle construction.

The following U.S. patent documents are related to the presentinvention: U.S. Pat. Nos. 7,419,713; 6,890,023; 6,537,413; 6,050,630;and 2005/0189674.

Other U.S. patent documents related to the present invention include:U.S. Pat. Nos. 5,502,930; 5,915,445; 6,102,464; 6,682,675; 6,790,026;6,682,676; 6,825,803; 6,981,863; 7,090,274; 7,909,379; 7,919,031;8,117,972; 2006/0255611; 2008/0185866; and 2011/0315310.

In view of the above, while the prior art shows a wide variety of marinehulls and associated construction materials and methods, a need stillexists for a marine hull which is not only relatively light, but alsosufficiently stiff or rigid and aerodynamically smooth, has a few numberof parts yet provides a large amount of interior space for passengersand/or gear and which allows the hull or watercraft to float and notsink even when there is a hole or tear in the hull.

SUMMARY OF EXAMPLE EMBODIMENTS

An object of at least one embodiment of the present invention is toprovide a deep-drawn, marine hull having a sandwich structure andwatercraft utilizing same which at least partially solves at least oneand preferably a plurality of problems associated with prior art marinehulls and watercraft.

In carrying out the above object and other objects of at least oneembodiment of the present invention, a deep-drawn, marine hull isprovided. The hull includes an outer skin having a waterproof outersurface, an inner skin having a compartment-defining outer surface and ashock absorbing, cellular core positioned between the skins. The skinsare bonded to the core by press molding. The cellular core has a 2-Darray of cells, each of the cells having an axis substantiallyperpendicular to the outer surfaces. Thickness of side walls of the hullis substantially uniform to maximize stiffness of the hull. The cellsabsorb energy of an impact at the outer surface of the outer skin bydeformably crushing. Air trapped within cells which are not completelycrushed or punctured by the impact provide the hull with buoyancy toallow the hull to float at the surface of a body of water.

The hull may form at least part of a watercraft such as a kayak.

The hull may further include at least one fastener mounted to the innerskin and capable of fastening or securing one or more objects in thecompartment of the hull.

Each fastener may include a fastener part having a length and a widthand a mounting part mounting the fastener part to the inner skin. Themounting part has a pair of holding faces that oppose each other anddefine a space therebetween. A portion of the inner skin is positionedin the space in engagement with the faces to prevent the fastener partfrom moving along its length relative to the inner skin.

The cellular core may be a honeycomb core.

The cellular core may have an open cell structure of the tubular orhoneycomb cell type.

The honeycomb core may be a thermoplastic honeycomb core.

The cells may include triangular, cylindrical, hexagonal or squarecells.

The open cells may have a diameter in a range of 2 mm to 10 mm.

The skins may be reinforced skins.

The hull may have a thickness in a range of 5 mm to 30 mm.

The skins may be thermoplastic skins and the core may be a thermoplasticcore.

At least one of the skins may be a fiber-reinforced skin.

At least one of the skins may be a woven skin.

Further in carrying out the above objects and other objects of at leastone embodiment of the present invention a watercraft is provided. Thewatercraft includes a deep-drawn hull section having an outer skinhaving a waterproof outer surface, an inner skin having acompartment-defining outer surface and a shock absorbing, cellular corepositioned between the skins. The skins are bonded to the core by pressmolding. The cellular core has a 2-D array of cells. Each of the cellshas an axis substantially perpendicular to the outer surfaces. Thicknessof side walls of the hull section is substantially uniform to maximizestiffness of the hull section. The cells absorb energy of an impact atthe outer surface of the outer skin by deformably crushing. Air trappedwithin cells which are not completely crushed or punctured by the impactprovide the hull section with buoyancy to allow the watercraft to floatat the surface of a body of water. The watercraft also includes a decksection bonded or joined to the hull section to form a water-resistantseal between the sections.

The watercraft may be a kayak.

The deck section may include an outer skin, an inner skin and a corepositioned between the skins and having a large number of cavities. Theskins of the deck section are bonded to the core of the deck section bypress molding. The watercraft may further include at least one fastenermounted to the outer skin of the deck section and capable of fasteningor securing one or more objects on the deck section.

Each fastener may include a fastener part having a length and a widthand a mounting part mounting the fastener part to the outer skin of thedeck section. The mounting part has a pair of holding faces that opposeeach other and define a space therebetween. A portion of the outer skinis positioned in the space in engagement with the faces to prevent thefastener part from moving along its length relative to the outer skin ofthe deck section.

Other technical advantages will be readily apparent to one skilled inthe art from the following figures, descriptions and claims. Moreover,while specific advantages have been enumerated, various embodiments mayinclude all, some or none of the enumerated advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an environmental view showing a prior art watercraft includinga single-wall, metal marine hull which has a hole formed therethrough tocause the watercraft to sink;

FIG. 2 is a view, similar to the view of FIG. 1, showing a differentwatercraft including a double-wall, plastic marine hull which has a holeformed therethrough to cause the watercraft to sink;

FIG. 3 is a side sectional view showing various separate layers of aprior art stack of thermoplastic-based layers of material;

FIG. 4 is a top perspective view, partially broken away and in crosssection, of the stack of FIG. 3 after low pressure, cold compressionmolding;

FIG. 5 is a view, similar to the view of FIGS. 1 and 2, showing awatercraft including a hull which has a hole formed at partiallytherethrough which does not cause the watercraft to sink since thewatercraft is constructed in accordance with at least one embodiment ofthe present invention;

FIG. 6 is view, partially broken away and in cross section, taken alonglines 6-6 of FIG. 1;

FIG. 7 is a view, similar to the view of FIG. 6, taken along lines 7-7of FIG. 2;

FIG. 8 is a view, partially broken away and in cross section, takenalong lines 8-8 in FIG. 5 wherein water is prevented from entering theinterior of the marine hull despite the hole in the marine hull;

FIG. 9 is a view, similar to the view of FIG. 8, taken along lines 9-9of FIG. 5 wherein water is not prevented from entering the interior ofthe marine hull but air trapped within cells of a cellular core of themarine hull prevent the watercraft from sinking despite the fact thatthe hole extends completely through the marine hull;

FIG. 10 is a top perspective view of the watercraft of FIG. 5;

FIG. 11 is a sectional view of the watercraft taken along the lines11-11 of FIG. 10;

FIG. 12 is an enlarged view, partially broken away and in cross section,taken within the phantom-line circle of FIG. 11 and showing the bondingor joining between hull and deck sections of the watercraft of FIG. 10;

FIG. 13 is a view, partially broken away and in cross section, takenalong lines 13-13 of FIG. 11 and showing a fastener component mounted ina hole formed through an outer layer or skin of the marine hull;

FIG. 14 is an end view of the fastener component of FIG. 13 prior toinsertion in the marine hull;

FIG. 15 is a side elevational view of the fastener component prior toinsertion;

FIG. 16 is a sectional view of the fastener component taken along lines16-16 of FIG. 15; and

FIG. 17 is a sectional view taken along lines 17-17 of FIG. 11 showingthe thickness of the cellular core being locally reduced in the areawhere the side walls transition into the bottom wall of the hull sectionso that the transition has a substantially continuous radius.

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

Referring again to the drawing figures, FIGS. 5 and 8-12 show a kayak,generally indicated at 110, which is a form of a watercraft constructedin accordance with at least one embodiment of the present invention. Thekayak 110 includes a hull section, generally indicated at 111 and a decksection, generally indicated at 112. Each of the sections 111 and 112preferably comprises either a compression-molded or deep-drawn compositecomponent having a sandwich structure and at least one, and, preferably,a plurality of fastener components, each of which is generally indicatedat 214 in FIGS. 13-16.

As best shown in FIGS. 8 and 9, the hull section 111 includes an outerlayer or skin 118 having a waterproof outer surface, an inner layer orskin 114 having a compartment-defining outer surface and a shockabsorbing cellular core 116 between the skins 114 and 118 and having a2-D array of cells. The skins 114 and 118 are bonded to the core 116 bydeep-drawing typically after pre-heating the skins 114 and 118. Theskins 114 and 118 are preferably fiber-reinforced thermoplastic layers.The thermoplastic may be a polyolefin such as polypropylene. Thethermoplastic may also be polyurethane. The fiber-reinforcement may be aglass mat, a natural fiber mat, a woven or non-woven mat.

The core 116 may be a cellular core having a thermoplastic honeycombstructure as shown in FIG. 4. The core 116 may also be made ofpolypropylene honeycomb and aluminum honeycomb. The resulting hullsection 111 typically includes a lightweight, low density core such asthe core 116 together with fiber-reinforced thermoplastic skins orlayers such as the skins 114 and 118.

The cells of the core 116 absorb energy of an impact at the outer skin118 of the hull section 111 by deformably crushing as shown in FIG. 8.The number, spacing, size, shape and material of the cells arepredetermined based on the anticipated types of impacts the hull section111 may encounter.

Each cellular core 116 or 116′ (i.e. FIG. 12 for the deck section 112)may be made as disclosed in the above-noted U.S. Pat. No. 7,919,031, orthe prior art cited therein. The cells may have a triangularconfiguration or the cells may form a honeycomb including cylindrical,hexagonal, or square cells. Other shapes are also possible such aswaves. The axes of the cells are perpendicular to the outer surfaces ofthe core 116 as well as the skins 114 and 118. Cell density (i.e. cellsize and wall stock) is adjusted as needed for expected impact force.The open cells typically have a diameter in a range of 2 mm to 10 mm andthe thicknesses of the cellular core with the skins 114 and 118 aretypically between 5 mm and 30 mm depending on the expected impact force.

The hull section 111 is typically deep-drawn as described in U.S. Pat.No. 6,981,863 ('863 patent). As described in the '863 patent, thedeep-drawing method generally includes positioning a blank ofthermoplastic sandwich material having a cellular core over a female diehaving an article-defining cavity defined by inner surfaces of thefemale die. The method also includes forcing an inner portion of theblank into the female die along a substantially vertical axis andagainst the inner surfaces of the female die to obtain deep-drawnmaterial. The method further includes clamping at least one outerportion of the blank immediately adjacent the female die to guide the atleast one outer portion of the blank to travel into the article-definingcavity at an acute angle with respect to the vertical axis during thestep of forcing so that thickness of at least one side wall of thedeep-drawn material is substantially the same as thickness of the blankof thermoplastic sandwich material and so that the deep-drawn materialdoes not significantly stretch or tear during the step of forcing. Themethod still further includes removing the deep-drawn material from thefemale die, and removing any excess material from the periphery of thedeep-drawn material to form the deep-drawn hull 111.

Preferably, the step of forcing includes the step of stamping and thestep of clamping is performed with a clamping force which increasesduring the step of forcing.

The stiffness of thermoplastic sandwich materials is due to the distancebetween its two skins 114 and 118 that gives a high moment of inertia tothe hull section 111. It is therefore important to preserve the distancebetween the skins 114 and 118 during the molding of the sandwich hullsection 111 in order to obtain the full stiffness potential of the hullsection 111. Any reduction of thickness causes a reduction of stiffness.

During the conception of a sandwich hull section 111 with a cellularcore 116, it is sometimes necessary to reduce the thickness of the hullsection 111 locally in order to obtain a specific shape. The stiffnessin that area will be reduced but can be maintained by the hull sectiongeometry. An example is that of a suitcase corner that gives thestiffness to the suitcase even though the part thickness is uniform. Asshown in FIG. 17, the thickness of the cellular core is locally reducedwhere the side walls transition into the bottom wall of the hull sectionso that the transition has a substantially continuous radius, asindicated at 140. The deep-drawing method disclosed in described in U.S.Pat. No. 6,981,863 allows the transition from the side surfaces to thebottom surface to have a substantially continuous radius, as exemplifiedby the FIG. 8 embodiment in the '863 patent, described in column 7,lines 34-37.

Hull sections made by the above-noted method are not wrinkled either ontheir compartment side or their water engaging side. As noted above,thickness of the side walls of the kayak 110 are relatively constant. Tohave a substantially consistent radius at the bottom wall of the kayak110, the honeycomb core 116 may be partially crushed during thedeep-drawing.

Referring again to FIGS. 8 and 9, cells of the core 116 absorb energy ofan impact at the outer surface of the outer skin 118 by deformablycrushing. Air trapped within cells which are not completely crushed orpunctured by the impact provide the hull section 111 with buoyancy toallow the hull section 111 and the kayak 110 to float at the surface ofa body of water 30 as shown in FIG. 5 despite the flow of waterindicated by arrows, F.

Referring to FIGS. 11 and 12, the deck section 112 is bonded or joinedto the hull section 111 to form a water-resistant seal 117 between thesections 111 and 112. The deck section 112 also preferably includes anouter skin 114′, an inner skin 118′ and a core 116′ positioned betweenthe skins 114′ and 118′ and having a large number of cavities. The skins114′ and 118′ of the deck section 112 are bonded to the core 116′ of thedeck section 112 by press molding. The deck section 112 may becompression or press molded using a variety of technologies which use alow temperature, compression molding apparatus. For example, the core116′ and the skins 114′ and 118′ are preferably generally of the typeshown in U.S. Pat. Nos. 6,537,413; 6,050,630; and 2005/0189674.

Referring to FIG. 13, after deep-drawing of the hull section 111 (orafter compression molding of the deck section 112) at least one holeand, preferably, a plurality of holes 124 are formed in the section 111(or 112) such as by cutting through the inner skin 114, through the core116 and right up to but not through the outer skin 118. A rivot-likefastener such as the fastener component 214 is positioned in each of theholes 124. Each of the fastener components 214 is generally of the typeshown in U.S. patent publications U.S. Pat. No. 7,713,011 and2007/0258786 wherein the preferred fastener component is called an M4insert, installed by use of a hydro-pneumatic tool both of which areavailable from Sherex Fastening Solutions LLC of New York.

One of the fastener components 214 is illustrated in FIGS. 14-16 priorto installation wherein during installation an outer sleeve of thefastener component 214 is deformed, the deformed component 214 beingshown in FIG. 13. The fastener component 214 typically has a relativelylarge annular flange, generally indicated at 226, an open end 228 and aplurality of integrally formed locking formations or wedges 230circumferentially spaced about an axis 232 of the component 214 on anannular face 234 of the flange 226 to prevent rotary motion of thefastener component 214 relative to the inner skins 114 afterinstallation. The wedges 230 grip into the outer surface of the innerskins 114 after the fastener component 214 is attached to the inner skin114.

In general, each fastener component 214 includes a cylindrical fastenerportion or part, generally included at 236, having a length and width,and a mounting portion or part, generally indicated at 238, for mountingthe fastener part 236 to the inner skin 114. The mounting part 238includes the annular holding face 234 and an annular holding face 242that oppose each other and define an annular space 244 therebetween. Anannular portion 146 of the inner skin 114 is positioned in the space 244in engagement with the faces 234 and 242 to prevent the fastener part236 from moving along its length or axis 232 relative to the inner skin114. The axis 232 is generally central to the fastener part 236 and theannular holding faces 234 and 242 are oriented to face axially along theaxis 232.

The fastener part 236 is threaded such as being internally threaded. Bybeing internally threaded, an externally threaded part of theabove-noted tool is threadedly secured to the fastener part 236 and thenrotated to move a distal end 246 of the fastener part 236 towards theopen end 228 of the part 236 thereby deforming an outer tubular sleeve248 of the fastener part 236 to form a second annular flange 250 havingthe holding face 242. Preferably, the outer surface of the sleeve 248includes a plurality of circumferentially spaced knurls 252 which formlocking formations on the holding face 242 of the annular flange 250 tofurther prevent rotary motion of the fastener component 224 relative tothe inner skin 114.

In like fashion, after compression or press molding the deck section 112holes similar to the holes 124 are formed in the deck section 112. Also,in like fashion, rivot-like fasteners such as the fastener component 214are positioned in each of the holes in the outer skin 114′ and the core116′ of the deck section 112.

As shown in FIGS. 5, 10 and 11, the rivot-like fasteners 214 mounted tothe outer skin 114′ of the deck section 112 are capable of fastening orsecuring one or more objects on the deck section 112 by means of strapsor leashes 122 and externally threaded anchors such as screws or bolts120. Such objects may include a paddle 13, a helmet 15 or a PFD 17 for apaddler 20 who may have encountered an underwater obstruction 32 (i.e.,FIG. 5) which caused a hole in the hull section 111 of the kayak 110.

As shown in FIG. 11, the rivot-like fasteners 214 mounted to the innerskin 114 of the hull section 111 are capable of fastening or securingone or more objects in the inner compartment of the kayak 110 viaexternally threaded anchors such as bolts or screws 120. Such objectsmay include safety equipment and/or gear such as hunting or fishinggear, as well as one or more seats 123 and/or padding, foot braces, etc.

Other types of fasteners may be used to removably secure one or moreobjects to the sections 111 and 112 of the kayak 110 such as snapfasteners or Velcro fasteners.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

What is claimed is:
 1. A deep-drawn, marine hull having side walls and abottom wall comprising: an outer skin having a waterproof outer surface;an inner skin having a compartment-defining outer surface; and a shockabsorbing, cellular core positioned between the skins wherein the skinsare bonded to the core by press molding, wherein the cellular core has a2-D array of cells, each of the cells having an axis substantiallyperpendicular to the outer surfaces, wherein thickness of deep-drawnside walls of the hull is substantially uniform to maximize stiffness ofthe hull, and the thickness of the cellular core is locally reducedwhere the side walls transition into the bottom wall of the hull so thatthe transition has a substantially continuous radius, the cellsabsorbing energy of an impact at the outer surface of the outer skin bydeformably crushing, wherein air trapped within cells which are notcompletely crushed or punctured by the impact provide the hull withbuoyancy to allow the hull to float at the surface of a body of water.2. The hull as claimed in claim 1, wherein the hull forms at least partof a watercraft.
 3. The hull as claimed in claim 2, wherein thewatercraft is a kayak.
 4. The hull as claimed in claim 1, furthercomprising at least one fastener mounted to the inner skin and capableof fastening or securing one or more objects in the compartment of thehull.
 5. The hull as claimed in claim 4, wherein each fastener includesa fastener part having a length and a width and a mounting part mountingthe fastener part to the inner skin, the mounting part having a pair ofholding faces that oppose each other and define a space therebetween, aportion of the inner skin being positioned in the space in engagementwith the faces to prevent the fastener part from moving along its lengthrelative to the inner skin.
 6. The hull as claimed in claim 1, whereinthe cellular core is a honeycomb core.
 7. The hull as claimed in claim6, wherein the honeycomb core is a thermoplastic honeycomb core.
 8. Thehull as claimed in claim 1, wherein the cellular core has an open cellstructure of the tubular or honeycomb cell type.
 9. The hull as claimedin claim 8, wherein the open cells have a diameter in a range of 2 mm to10 mm.
 10. The hull as claimed in claim 1, wherein the skins arereinforced skins.
 11. The hull as claimed in claim 1, wherein the hullhas a thickness in a range of 5 mm to 30 mm.
 12. The hull as claimed inclaim 1, wherein the skins are thermoplastic skins and the core is athermoplastic core.
 13. The hull as claimed in claim 1, wherein at leastone of the skins is a fiber-reinforced skin.
 14. The hull as claimed inclaim 1, wherein at least one of the skins is a woven skin.
 15. The hullas claimed in claim 1, wherein the transition has a substantiallyconstant radius.
 16. A watercraft comprising: a deep-drawn hull sectionhaving side walls and a bottom wall including: an outer skin having awaterproof outer surface; an inner skin having a compartment-definingouter surface; and a shock absorbing, cellular core positioned betweenthe skins, wherein the skins are bonded to the core by press molding,wherein the cellular core has a 2-D array of cells, each of the cellshaving an axis substantially perpendicular to the outer surfaces,wherein thickness of deep-drawn side walls of the hull section issubstantially uniform to maximize stiffness of the hull section, and thethickness of the cellular core is locally reduced where the side wallstransition into the bottom wall of the hull section so that thetransition has a substantially continuous radius, the cells absorbingenergy of an impact at the outer surface of the outer skin by deformablycrushing, wherein air trapped within cells which are not completelycrushed or punctured by the impact provide the hull section withbuoyancy to allow the watercraft to float at the surface of a body ofwater; and a deck section bonded or joined to the hull section to form awater-resistant seal between the sections.
 17. The watercraft as claimedin claim 16, wherein the watercraft is a kayak.
 18. The watercraft asclaimed in claim 17, wherein the deck section includes an outer skin, aninner skin and a core positioned between the skins and having a largenumber of cavities wherein the skins of the deck section are bonded tothe core of the deck section by press molding.
 19. The watercraft asclaimed in claim 16, further comprising at least one fastener mounted tothe outer skin of the deck section and capable of fastening or securingone or more objects on the deck section.
 20. The watercraft as claimedin claim 19, wherein each fastener includes a fastener part having alength and a width and a mounting part mounting the fastener part to theouter skin of the deck section; the mounting part having a pair ofholding faces that oppose each other and define a space therebetween, aportion of the outer skin being positioned in the space in engagementwith the faces to prevent the fastener part from moving along its lengthrelative to the outer skin of the deck section.
 21. The watercraft asclaimed in claim 16, wherein the transition has a substantially constantradius.